What is this triangular symbol?

While waiting for the subway to arrive, I noticed this mysterious symbol between “PRINCE” and “ST.” This is not a mistake of any kind. All of the signs at the station had this little triangle, and whoever created these signs put a significant amount of effort in inserting it. (Just look at how it is tiled.) Obviously this was something important for the artist who created this mosaic sign. What could it mean? It could not be a dash. Firstly, a dash would be inappropriate for this context. Secondly, if it were meant as a dash, it would have been much easier to draw a straight line out of these square tiles (instead of a triangle).

It's Pythagoras' triangle. In its most esoteric form, the base is the mother, the height is the father, and the hypotenuse is the son aka: the perfected man. Its place on the sign of Prince St doesn't surprise me as princes (as well as other nobles and the like) look to the allegory as a part of some masonic religious icon.

This is not a case of English diction gone awry, but rather Masonic imagery cleverly disguised in a sign. I wouldn't be surprised if there's a square and compass surrounding a "G" placed elsewhere in the station.

That would be very interesting if that were true, but I'm not sure about that. As you can see below, it's quite off from where the true Pythagorean triangle should be (3-4-5 ratio). If the artist truly believed in mathematical beauty, I think he/she would have been much more precise.

Patrick´s explanation is the only correct one. See any Roman age inscription writen in stone. The triangular shape of a dot is determined by the technique of writing in stone - it is determined by the shape of the employed tool and by the character of the material - stone. The dots in Roman age stone-carved inscriptions are always triangular. This mosaic inscription only wants to look like a Roman age inscription written in stone.

It may be this or that, but it has to have a purpose. What's that? The creator (author) wants to convey a specific meaning by "the writing on the wall". In other words, that is to distinguish 'the writing' from other commonly and readily interpreted terms.In this case other interpretation like princet or Prince's St or princest (sic) etc. are to be specifically kept at bay, by way of interjecting this symbol.

This sign is probably designed for people to read it from a distance and in a hurry. The mark can act like a visible space. Like serifs make reading text easier without the reader noticing them, this mark could be something a person doesn't consciously see from a distance but his brain picks up. This way he doesn't see Princest, but Prince St. (For that matter, maybe the designer wanted to avoid an offensive word that appears without the space and then had to put it on all the signs for consistency!)

It's just a freakin interpunct!!! The mosaic is roman, the romans wrote in Latin, and way back when, they didn't use spaces to separate words, so they used and interpunct. Mosaic=Roman=Latin=Interpunct!!